A printer is used as an image forming apparatus which forms a specified image on printing paper. Especially, various optional devices may be connected to a business-use printer, and an image forming apparatus is configured by connecting an optional device to a printer. An optional device may be a paper ejection device, and paper printed by a printer is ejected to a paper ejection device.
Patent Documents 1 and 2 disclose the technology of connecting a plurality of paper ejection device to a printer. In the technology according to the Patent Document 1, a remainder detecting sensor is provided in each of a plurality of stackers, and the remainders of the stackers are compared with the number of printed sheets for one printing job, thereby selecting a stacker. In the technology according to the Patent Document 2, a plurality of stackers are provided, and the first stacker to become full (the stacker which has first become full) is displayed as blank, thereby changing the destination stacker for paper ejection.
[Patent Document 1] Japanese Laid-open Patent Publication No. 5-155511
[Patent Document 2] Japanese Laid-open Patent Publication No. 2004-338916